Evaluation of Oxygen Reserve Index (ORi) in Obese and Non-Obese Patients Over 65 Years Old

Evaluation of Oxygen Reserve Index (ORi) in Obese and Non-Obese Patients Over 65 Years Old Scheduled for Elective Surgery Under General Anesthesia

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT07679724

Enrollment

Registered

2026-07-01

Start date

2023-11-01

Completion date

2024-07-01

Last updated

2026-07-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Elderly (People Aged 65 or More), Obesity &Amp;Amp; Overweight, Oxygen Reserve Index

Brief summary

After obtaining ethical committee approval, this single-center, prospective, observational study included volunteer patients of both sexes, aged 65 years and older, with ASA II-III risk scores, who were scheduled for elective surgery with endotracheal intubation under general anesthesia (GAA). 90 patients were divided into two groups: those with normal BMI (19 \< BMI \< 25 kg/m² (GROUP 1)) and those who were obese (30 \< BMI \< 40 kg/m² (GROUP 2)). In addition to standard ASA monitoring, a finger sensor (Rainbow® SET, Masimo Inc., Irvine, Ca., USA) was implanted for ORi measurement, and baseline values were recorded. Patients were preoxygenated until EtO2 (endtidal oxygen) concentration reached at least 85%. After ORi reached a plateau level, general anesthesia was induced and endotracheal intubation was performed. After confirming the tube's position, the breathing circuit was disconnected from the endotracheal tube, and patients were allowed to be apneic until SpO2 reached 94%. Throughout this process, patients' other vital signs, SpO₂, and ORi were continuously monitored. The time elapsed when ORi triggered an alarm, when SpO2 reached 97%, and when SpO2 reached 94% was recorded. The 'ORi warning time', 'SpO2 warning time', and the 'additional warning time provided by ORi' (the difference between 'ORi warning time' and 'SpO2 warning time') were recorded.

Interventions

None listed

Study design

Observational model

CASE_CONTROL

Time perspective

PROSPECTIVE

Eligibility

Sex/Gender

ALL

Age

65 Years to No maximum

Healthy volunteers

Yes

Inclusion criteria

Patients of both sexes aged 65 years and older with ASA II-III risk scores who are scheduled to undergo elective surgical procedures with endotracheal intubation under general anesthesia.

Exclusion criteria

* Patients under 65 years of age * Patients with heart and lung disease * Patients in situations where the patient is unable to cooperate (e.g., dementia, Alzheimer's) * Patients suspected of having airway difficulties

Design outcomes

Primary

Measure	Time frame	Description
Oxygen reserve index (ORi) warning time, SpO2 warning time, and added warning time defined as the difference between the two	15 minutes after preoxygenation	The primary aim of this study was to determine whether ORi provides an early warning of impending desaturation compared to pulse oximetry in both obese (30 \< BMI \< 40 kg/m²) and normal body mass index (19 \< BMI \< 25 kg/m²) patients over 65 years of age scheduled for elective surgery will be assesed until SpO2 drops to 94%

Secondary

Measure	Time frame	Description
Oxygen reserve index (ORi) warning time, SpO2 warning time, and added warning time defined as the difference between the two	15 minutes after preoxygenation	The secondary objective of this study was to compare the additional stimulus duration provided by ORi in obese (30 \< BMI \< 40 kg/m²) and normal body mass index (19 \< BMI \< 25 kg/m²) patients over 65 years of age will be assesed until SpO2 drops to 94%

Countries

Turkey (Türkiye)

Outcome results